Damping gyroscopic compasses



June 24, 1930. H. TANNER 1,765,548

DAMPING GYROSCOPIC COMPASSES Filed April' 25, 1925 iNVENTOR.

Patented June 2 4,

um'raosmras PATEN OFFICE Hana? L. TANNER, or BROOKLYN, NEW 'Yonx, nssmiioa r mm) msrnimm'r comm, me, or 1.01m rsnann crrx, Nn'w xonx, a coaromnon or NEW-YORK nun-Ins emoscorrc conrassns Application mes April as, 1025. Serial M12539,

This invention relates to damping the oscillations about the meridian of the gyroscopic element of a gyroscopic compass and more particularly to damping means adapted for use with a gyroscopic com ass of the type disclosed in my United tates' Letters lgagtgnt No. 1,701,283, granted. February 5, 1 I! I r v i v The advantageous form of gyroscopic com- 10 pass disclosed in" my'said application is so constructed that the degrees of freedom of its gyrosco ic element about two mutually perpendicu ar supporting axes may be suppressed in order to cause the element to fol- 1 low the movement of the craft over the sur- 1 face of the earth and maintain its normal relation to this surface independently of latitude." By virtueof this construction the effect upon the element of'acceleration and retardation pressure due. to changes in speed of the craft will be 'automaticall taken care of, and such corrections, as ma e necessary V to meet new conditions of spec may be easily lied.

ap a Ks illustrated in said application, the gyro- ,scopic compass comprises a mass, such as the rotor of an electricall driven gyroscope, which is arran ed to spin about an axishaving a lar e an substantially constant inclin- 0 atlon to t e surface of the earth and normally bearing a fixed relation to the plane of the meridian; and a surrounding case which serves as a support for the mass and may turn in the lane ofthe mass about the in- .clined axis o --'the latter iudependentl' of the rotary movement of the mass within t e case. The case is mounted within an inner su porting member upon an axis lying in 0 plane of the case; and the inner supporting 46 member is mounted upon ahorizontal axis perpendieular to the supporting axis. of the case within another supporting member which in turn is'mounted upon a horizontal axis within a horizontal inner frame, or the,

inner supporting member may in some Tses motor,

be mounted directlyupon the frame upon a horizontal axisperpendicular to the supporting axis of thecase. Such inner frame-is movably mounted upon an outer frame which has a fixed relation to the craft upon which the .compa'ssis carried. I

When the gyroscopic element occupies its normal position with respect to the oints of the "com ass, that is, when [it has sett ed upon the merldian, relative movement between the frames due to'chan'ge in course of the craft will tend to turn the c y as about the rotor and 'dis lace the parts of he contact mechanismv wit respect to "each (g 'the driving motor to turn the gnner frame and the casein a; direction oppos ther. This will cause to to that in whichthese members willtend to be turned by the movement of the craft and thisreverse movement will continue until'the parts of the contact mechanism are brought back to their normal relation thereby stopping the It is an object of this-invention to provide oscillation damping means especially 7 adapted for use with gyroscopic compasses of the ty e referred to.

A furt er objectis to provide an im roved method of damping the-oscillations of yroscopic compasses especially such as disc osed in said Patent 1,701,283. 4 75 1 According to one form of ,the invention use is made of liquid containing reservoirs mounted on the element at o posite sides of the north-south plane throng the center of the apparatus and at oppositesides of the east-west vplane through the center of the apparatus, and a reservoir connecting pipe or tube of such interior dimensions that, in view of the slow oscillations of the yrosco ic element, the flow through the tu e'will e substantiall unrestricted. I

Accor ing to another form of the inven-. tion, the li uid is contained in a tube arranged in t e same eneral manner as the first mentionedliqui containing device but a by displacin the axis 55 from the center the tube is of substantially uniform cross section throughout its entire length.

The particular nature of the invention as well as other objects and 'advanta es thereof -wi1l appear more clearly from a escription Fig. 3 is a simplified plan of a gy'roscopic element havin another embodiment of the invention applied thereto.

' Referring to Figs. 1 and 2, the instrument comprises a gyroscopic rotor 1 of any suitable construction, the axis of which is mounted in upper and lower bearings of a case 2 surrounding the rotor. The case 2 is provided with trunnions 3, 3 mounted in bearings in an inner ring 4 provided in turn with trunnions 5, 5 mounted in bearings in a second ring 6, hereinafter referred to as the stabilized ring of the instrument. The gyroscopic element and its supporting ring 4 are mounted in an inclined position as shown most clearly in the elevational view, Fig. 2,

of gravity 0 the element so that the element is pendulous and maintains a certain inclination to the surface of the earth when the rotor is not spinning. This angle will be constant for all positions of the compass.

When the rotor iss inning the inclination of the element will di er from its inclination when the rotor is at rest by a second angle which depends upon the latitude and a third angle which depends upon the east-west component of the speed of the craft upon which the compass isicarried.

The stabilized ring 6 is provided with trunnions 7, (disposed at right angles to the trunnion axis 5-;5 and. in the plane of the trunnion axis 3-3. The trunniohs 7, 7 are mounted in bearings inan inner frame or shell 8 adapted to be power driven and bearing a scale raduated in units of angular measure.

servo motor 12 in any suitable manner, as by means of a pmlon-meshlng with a gear at-' This rame 8 is rotatably mounted within an outer frame or'shell 9 as by means of balls 10. The frame 9 bears the lubbers' line of the compass and is provided with trunnions 11, 11 adapted to fit in hearings in the gimbal rings of the binnacle, which havebeen omit ted from the drawing for the sake of simplicity. p

The element 8 is adapted to be driven by a tached to the element. The circuit of the servo motor is controlled by a device consisting of a contact 13 mounted on the case and adapted to engage one or the other of two contacts 14 mounted upon the ring 4 to cause the servo motor to rotate in one direction or the other. For simplicity the circuit connections between the device and the motor have been omitted. v

The stabilized ring 6 is provided with a pair of depending brackets 15 disposed in the north-south plane and carrying at their lower ends a ring 16 within which is mounted a stabilizing gyroscope 17 having its rotor axis substantially vertical. ring 16 is a member l8 which at its other end is attached to an adjusting device 19 mounted on the stabilized ring 6, whereby the planes of the rings may be adjusted relatively to each other. In considering the operation of the instrument described above it will be assumed that the rotor 1 of the main gyroscope is turning clockwise as viewed from above in Fig. 1. It will also be assumed that the contact 13 occupies its neutral position with respect to the two cooperating contacts 14 so that the servo motor 12 is not energized. It will be most convenient to regard the element 8 as having been turned in a clockwise direction through 90 from the position shown in Fig. 1 so that the axes 3-3 and 77 be in an east-west direction with the high side of the gyroscopic element toward the east. v

In accordance with the principle of the gyroscope the plane of rotation of the rotor 1 will remain fixed in space. As the earth turns from under the rotor due to its rotation, the high side of the rotor will rise relatively to the surface of the earth carrying the case with it. This will cause the pendulous mass of the rotor and case to be shifted from its Connected with the position of equilibrium, or, in other words,

of the inclined ring 4. Under the conditions assumed herein, the north side of the case will move up and the south side will move down, so that the contact 13 will be shifted from its neutral'position with respect to the contacts 14 into engagement only with the con-' tact lying'toward the south, thereby energizing the servo motor 12 to rotate in a direction to turn the-power driven element 8 counterclockwise to carry the axes 3-3 and 77 toward the meridian. As the movable parts of the instrument turn toward the meridian the inclination of the gyroscopic element will gradually increase as the earth continues to turn away from under' it,'thus increas ing the torque about the axis 5-5. The

rotor and case will therefore precess' about the axis 3-3 at an increasing rate, and the contacts 13 and 14 will kee the servo motor 12 energized and the elem nt 8 in motion. The axes 3-3 and 7-7 will thus be carried ast the meridian and toward the west. 1 his westerly movement will continue until the contact 13 again assumes its neutral position with respect-to the contacts 14 to deenergize the servo motor 12. This will not occur until precession about the axis 3-3 has ceased due to the absence of torque about the axis 5-5. This last named condition will obtain when the parts of the instrument have-- turned so far toward the west that the gyro; sco ic elementlies at its normal inclination wit respect'to the surface of the earth due to thefact that in the'new position of the element the earth is turning toward the plane of the rotor instead of away from it as at the beginnin of the cycle of operations described a ove. j

During the movement of the parts-from east ,to west there will be a relative movement of the case with respect to the rotor about the axis of the latter entirely apart. from-the rotation of the rotor within the case. In other words, durin meridian seeking oscillations,

the case 2 'wil turn in the plane-of therotor about the axis common to it and therotor, While the rotor is spinning about this same axis. At the same time that the case is turnsurface of the earth due to the fixity of the plane of-rotation of the rotor. This depression of the high side of the element Wlll. result in shifting its center of gravity, toward the east from its normal position, thus produc- ,'ing about the horizontaPaxis-5-5 a torque which will be inthe opposite direction to that produced whenthe elementwas at its eastern limit of oscillation. This torque will cause precession of the rotor and case-about the axis 3-3 in such a direction'as to elevate the north side of the case and de 'ress the south side relatively to the incline ring 4. 'As a result of this precession the contact 13.will be shifted from its neutral position with respectto the contacts14 into engagement only with the one lying toward the south, thus energizing the servo motor 12 to turn the power driven element 8 in a clockwise direction thereby swinging the axes-3-3 and 7-7' across the meridian toward the east. As the parts move from the west'toward the meridhau the inclination of the gyroscopic element I with respect to the surface of the earth will continue to decrease since the earth is turning toward the element. The torque about the axis 5-5 due to the shifting of the center 01- gravity of the element-will thus be in-.

creased, aswill also the'precession of the rotorand case about the axis 3-3. The instrument will cross the meridian from west to, east with the axis 3-3 depressed as far below its normal inclination as it was raised above thisinclination when it crossed the meridian from east to west.

During the west to east movement the case will turn about the rotor axis in the o posite direction to that in which it turns during the movement from east to west, and the case will also have a movement of precession about the axis 3-3 in the opposite direction. The resultant movement of the case will be about a vertical axis through the intersection of the axes 3-3 and 5-5 but in the opposite direction to that in which it turned during the east I to west oscillation.v

If the gyroscopic element be unaffected b any other external'forces-its oscillations wi l gradually diminish in am litude due tofric tion; and it will ultimate y reach a settlin point withits axis 3-3 lying in the plane'n the meridian and at a definite angle which is the resultant of combining the angle of in-l clination When the rotor is at rest; an angular variation from such inclination for the particular latitude of the compass when its rotor is spinning; and an angular variation in accordance with the east-west component of the speed of the craft so that the gyroscopic element may follow the movement of thecraft over the earths surface. The first mentioned angular variation is such that the pendulousness of the element will maintain a torque about the axis 55 to cause the element to precess about the axis 3-3 at an angular velocity equal to the component of the angular velocity of the earth about an e earth about its axis. Y i v 'If the course of the craft. be changed theresulting movement in azimuth of the outer elementwill tend to carry along the inner ed thereon. As the ring 4 moves it will turn shell or element B and the rings 6 and '4; mountthe case 2 about the incllned axis of the rotor and will itself be slightly tilted about the spect to the case. There will he therefore a displacement of the contacts 13 and 14 from their neutral positions relative to each other,

in a direction to cause the servo motor 12 to" turn the element 8 in'the reverse direction and consequently turn the ring4 and case 2 until axis 3-3 from its normal position with re- 1 the contacts 13 and 14 are brought back to their relatively neutral positions. The instrument willopera'tein this manner when;

110 axis parallel to the axis 3-3, whereb the ele- 'ment follows the movement of t ever there is any yaw of the craft, the servo motor maintaining the compass card in its true position while the element 9 bearing the lubbers line will turn in accordance with the movement of the craft.

A simple form of compass such as has been described above will, however, require such a long time to settle on the meridian that it would be unsuited for use even on land unless used for navigational purposes.

According toone form of my invention, as shown in Figs. 1 and 2, use is made of liquid damping device comprising a pair of liquid containing reservoirs 20 and 21 mounted on the upper part of the case at opposite sides of the vertical planes through the axes 3-3 and 5-5, respectively and substantially equidistant from the line of said planes, and a connectin tube 22 of such dimensions that, in view OI the comparatively slow movements of the case 2, the fiow of the liquid therethrough may for all practical purposes be considered as unrestricted.-

The equilibrium position of the gyroscopic element, including the liquid damping meansunder consideration, is shown in Fig. 2. Assuming that it starts from an east position the inclination of the element will be increased as the earth turns'from under it and the liquid will flow from reservoir 20 into reser-' voir 21 One eifect of such increase of weight of the contents of reservoir 21 and decreaseof weight of the contents of reservoir 20 is to produce a torque which may be resolved into two components, one about the axis 5-5 andthe other about the axis 3-3.

Such component torque about the axis 5-5- reduces the endulousness of the gyroscopic element slig tly and decreases its. meridian seeking tendencv. The effect of this component maybe ofiset by rendering the case 2 sufliciently pendulous.

The effect of the component torque about the axis 3-3 is to cause precession about the axis 5-5, thus depressing the high side of 'the gyroscopic element and elevating the lower side. The inclination of the-element is therefore reduced below that which would exist in the undamped form of instrument and the amplitude of the oscillation toward the west is therefore reduced. As the element swings back from west to east the damping means will again act to lessen the deviation of the axis from its normal inclination as compared with the undamped instrument. The

inclination of the axis thus rapidly approaches its normal value during subsequent oscillations and finally settles in the plane of the meridian. I I

In carrying out the invention in another way, as-shown by Fig. 3, use may be made of a single tube 23 arranged with its ends at opposite sides of the vertical plane through the axis 3-3 but normally at one side of the vertical plane through the axis 5-5. When the inclination of the gyroscopic element is Y changed more of the liquid will flow to the depressed end to produce a component of torque about the axis 5-5 and a component of torque about the axis 3-3. The torque about the axis 5-5 merely efiects the pendulousness of the gyroscopic element and its meridian seeking tendency and may be ofi'set by rendering the case sufficiently pendulous. The effect of the component about the axis 3-3 is to cause precession about the axle 5-5 and a damping action will be produced I in the same way as with the damping means comprising reservoirs 20 and I i In this form of gyroscope the'efi'ect of rolling and pitching is overcome by the stabilizing gyroscope 17, but effects due to changes of latitude and other causes must be compensated and this may be done bymeans including the adjusting device 19 as more fully described in said Patent 1,701,283.

For the purpose of accurately balancing the main gyroscope about the axis 3-3 the case 2 is provided with a pair of brackets 24 supporting a screw 25 on which is thread- 100 ed a weight 26, the arrangement bemg such that by turning the weight about the screw 25 it may be moved in a direction perpendicular to the axis 3-3. I

While preferred embodiments of the m- 105 vention have been shown and described, it should be understood that the invention may be embodied in other forms and that various changesin the details of construction of the elements without departing from the principle of the invention as defined in the appended claims.

I claim: I 1. In a gyroscopic compass,*a rotor, a case within which the rotor is mounted to spin about an axis inclined to the surface of the earth at asubstantial angle to the vertical and to the'horizontal and normally lying in the plane of the meridian, and means for damping the oscillations of the rotor axis about the meridian comprising two liquid containingreservoirs mounted on the case on opposite-sides of the vertical plane through the spinning'axi's and spaced apart in the directionof; that plane, and means'forming of the instruments may be made 0 I nation with a gyroscopic element including a rotor having its axis of rotation inclined to the surface'of the earth at a substantial angle to the vertical and to the horizontal and a case therefor, of liquid damping means rigidly mounted on and dia onally across the case with respect to a vertical plane containing the axis of rotation, saidmea'ns being so constructed that the center of gravit of the contained liquid shifts substantially 1n phase with the changes in inclination of its gyroscopic element to the surface of the earth.

In testimony whereof I aflix my si nature.

- HARRY L. TAN ER. 

